Promoting Stretching Exercise to Reduce Cardiovascular Health Risk in Late Pregnant Women With Obesity: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Promoting Stretching Exercise to Reduce Cardiovascular Health Risk in Late Pregnant Women With Obesity (NCT04291560), a randomized na study. The primary outcome is Change in Systolic Blood Pressure From Baseline (27 Gestational Weeks) to 32 Gestational Weeks.

2. Clinical Question

This is a comparison of two assigned activity approaches, not a comparison of stretching with no activity. Both arm descriptions include usual care and supportive calls, while the assigned exercise differs. That distinction matters when interpreting the contrast: the estimated difference concerns the stretching program relative to the specified usual-care control, not the isolated effect of receiving any exercise or support.

The trial title frames the objective as reducing cardiovascular health risk in late pregnancy. The primary endpoint focuses on systolic blood pressure over a short interval, while listed secondary outcomes include pregnancy complications and delivery outcomes. Those outcomes address related but distinct questions. The registry record does not report a single combined clinical question covering all listed outcomes, nor does it report results for every outcome that was registered.

3. Trial Design

The registry describes a randomized, single-masked, parallel-group trial sponsored by the University of North Carolina, Chapel Hill. Enrollment is listed as 224, and the trial status is completed. The listed start date is 2020-03-01, and the listed primary completion date is 2024-10-23. The record lists the phase as not applicable.

Participants were assigned to Prenatal Heart Smart Intervention or Usual Care (Control). In the intervention arm, usual care and facilitator support calls were combined with a home sequential static stretching exercise program, described as occurring 5 days per week for 10 weeks. In the control arm, usual care and supportive calls were combined with moderate-intensity walking, also described as occurring 5 days per week for 10 weeks. The brief summary characterizes usual care as moderate/vigorous activity 30 minutes daily, 5 days per week. The identity of the masked party and further details about masking are not reported in the registry record.

The primary endpoint is a continuous measure: change in systolic blood pressure from baseline, approximately 27 gestational weeks, to approximately 32 gestational weeks. The registry states that only participants who completed blood pressure measures at their 32-week follow-up visit are included in the primary endpoint population. The posted arm summaries contain 33 participants for the stretching group and 39 for usual care for this endpoint. These endpoint-specific counts are not the same as the enrollment figure; the registry record does not explain the difference.

The registry lists 22 outcome measures and 12 posted secondary outcomes, while the analysis count is listed as 0. No sponsor-reported analysis is listed for the three secondary outcomes with numerical results in the record. Details such as the randomization procedure, allocation concealment, identity of the masked party, and the original statistical analysis plan are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: 224 participants consented during early pregnancy. After consenting, participants underwent a run-in period until reaching approximately 27 weeks gestation, at which point a baseline visit was scheduled. 108 participants completed this baseline visit, and thus were randomized to one of the study arms.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Only includes participants who completed blood pressure measures at their 32 week follow-up visit.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Change in Systolic Blood Pressure From Baseline (27 Gestational Weeks) to 32 Gestational Weeks, measured over Baseline (approximately 27 gestational weeks) to approximately 5 weeks after baseline (approximately 32 gestational weeks).

The primary endpoint is change in systolic blood pressure, measured in mmHg, from baseline at approximately 27 gestational weeks to approximately 5 weeks later, at approximately 32 gestational weeks. The registry describes the reported measure as the average systolic blood pressure measurement between two measurements at the assessment times. It also states that three total measurements will be taken, with the first removed and the second two averaged. The registry description does not clarify further how that measurement procedure applies across the two time points.

Change is useful because it expresses how a continuous measurement moves over the period of interest, rather than comparing only the final measurement. The treatment contrast then asks whether the average change differs between the randomized groups. Systolic blood pressure is a cardiovascular measure, so it is relevant to the trial’s stated focus on cardiovascular health risk in late pregnancy. That relevance does not make it a complete measure of maternal health or pregnancy outcome: it is one physiological endpoint, assessed over a defined interval.

The registry restricts the primary endpoint population to participants who completed blood pressure measures at the 32-week follow-up visit. Thus, the reported endpoint summaries do not describe every enrolled participant. The registry record does not report how missing follow-up measurements were handled beyond defining the endpoint population this way, or whether a different analysis population was used for the sponsor’s analysis.

7. Results Posted in the Registry

• Prenatal Heart Smart Intervention: mean 0.73 versus -1.56 on control; difference 2.29 (95% CI -1.54 to 6.12), standardized effect d = 0.28; z-test p = 0.242.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Onset of Preeclampsia Anytime Between Baseline (27 Weeks Gestation) and the End of Pregnancy

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Prenatal Heart Smart Intervention: 7.5% (4/53) versus 12.7% (7/55) on control; risk difference -5.2 percentage points (95% CI -16.5 to 6.1), risk ratio 0.59 (0.18–1.91); unadjusted two-proportion z-test p = 0.374.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Prenatal Heart Smart Intervention and the control. The interval gives the range of effects that remain compatible with the data.

Onset of Pregnancy Induced Hypertension Anytime Between Baseline (27 Weeks Gestation) and the End of Pregnancy

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Prenatal Heart Smart Intervention: 28.3% (15/53) versus 38.2% (21/55) on control; risk difference -9.9 percentage points (95% CI -27.5 to 7.8), risk ratio 0.74 (0.43–1.28); unadjusted two-proportion z-test p = 0.276.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Prenatal Heart Smart Intervention and the control. The interval gives the range of effects that remain compatible with the data.

Onset of Gestational Diabetes Anytime Between Baseline (27 Weeks) and the End of Pregnancy

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Prenatal Heart Smart Intervention: 11.3% (6/53) versus 10.9% (6/55) on control; risk difference 0.4 percentage points (95% CI -11.4 to 12.3), risk ratio 1.04 (0.36–3.02); unadjusted two-proportion z-test p = 0.946.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Prenatal Heart Smart Intervention and the control. The interval gives the range of effects that remain compatible with the data.

The three secondary outcomes with numerical results concern onset of preeclampsia, pregnancy-induced hypertension, and gestational diabetes between baseline and the end of pregnancy. Across these outcomes, the unadjusted estimates do not show a consistent, precise separation between the randomized groups: each interval includes no difference, and uncertainty remains in the possible direction and size of the contrast. This broad pattern is compatible with the imprecision seen for the primary blood pressure comparison, but the endpoints measure different things over different time frames.

The primary endpoint is a continuous change in systolic blood pressure over approximately 5 weeks. The secondary outcomes are binary pregnancy events recorded over approximately 13 weeks. A blood pressure change and the occurrence of a diagnosis are not interchangeable outcomes, so agreement or disagreement between them would not by itself validate or invalidate the other. These secondary results provide related clinical context, but they do not replace the primary endpoint or establish a broader effect across maternal outcomes.

Unadjusted secondary results carry less weight as a set when multiple outcomes are examined. Even if each individual comparison is calculated correctly, considering many results increases the chance that at least one may appear notable by chance. Interpretation also depends on whether outcomes and analyses were prespecified and whether adjustments were planned. The registry record does not report a multiplicity strategy, analysis plan, or sponsor-reported analyses. Therefore the posted secondary estimates are best treated as exploratory descriptive comparisons, rather than as a collection of independent confirmatory tests.

The registry lists additional secondary outcomes, including eclampsia, preterm delivery, cesarean section, a composite maternal outcome, and intrauterine death, but numerical results for those outcomes are not reported in the registry record. It lists 12 posted secondary outcomes overall, while numerical group comparisons are available for only the three. The overall pattern can therefore be characterized only for the outcomes with posted numerical data; it cannot establish a pattern across every registered secondary endpoint.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Onset of Preeclampsia Anytime Between Baseline (27 Weeks Gestation) and the End of Pregnancy
• Onset of Eclampsia Anytime Between Baseline (27 Weeks Gestation) and the End of Pregnancy
• Onset of Pregnancy Induced Hypertension Anytime Between Baseline (27 Weeks Gestation) and the End of Pregnancy
• Onset of Gestational Diabetes Anytime Between Baseline (27 Weeks) and the End of Pregnancy
• Preterm Delivery at End of Pregnancy
• Elective or Emergency Cesarean Section at End of Pregnancy
• Composite Score of Maternal Outcomes at the End of Pregnancy
• Intrauterine Death at End of Pregnancy

9. Statistical Interpretation

10. Statistical Methods Explained

What is the mean difference?

The primary comparison is a difference between group means. Each group’s summary describes the average change in systolic blood pressure, and the mean difference contrasts those averages. The reported direction is intervention minus control. A positive estimate therefore means the observed average change was higher in the intervention group; a negative estimate would mean it was lower. This direction describes the numerical contrast, not whether the result is beneficial or harmful. Interpretation of clinical importance requires context that the registry record does not provide, including a threshold for a meaningful blood pressure difference.

For this endpoint, the two group means are 0.73 mmHg and -1.56 mmHg, and the reported mean difference is 2.29 mmHg. The comparison is an unadjusted recalculation from the posted summaries. An unadjusted comparison uses the group summaries without accounting for additional variables. It is relatively straightforward to understand, but it may not match a prespecified analysis that adjusts for baseline blood pressure or other characteristics. The registry record does not report whether the sponsor conducted such an analysis.

What does the standard deviation describe?

The standard deviation describes how spread out individual measurements or changes are around their group mean. The primary endpoint standard deviations are 8.21 mmHg and 8.34 mmHg. A standard deviation is not the same as a confidence interval: it describes variation among observations, whereas a confidence interval describes uncertainty about an estimated quantity. A group can have substantial person-to-person variation while its mean is estimated with greater or lesser precision depending on the amount of information available.

In general, the mean and standard deviation summarize a continuous outcome when an average is meaningful and the distribution is sufficiently well behaved for that summary to be informative. If data are strongly skewed or contain unusual values, a mean and standard deviation may not fully describe the distribution. Distributional diagnostics are not reported in the registry record, so no conclusion about the shape of the blood pressure change distribution can be drawn from these summaries alone.

How should the confidence interval be understood?

A confidence interval gives a range of estimates compatible with the observed data under the method used to construct it. In repeated studies using the same procedure, confidence intervals would vary from study to study; the stated confidence level concerns the long-run performance of that procedure. It is not a probability statement about the specific true effect after observing the data. The primary interval, -1.544 to 6.124 mmHg, includes no difference and values on either side of it. This breadth indicates that the estimate is not precise enough to distinguish clearly among those possibilities.

The registry does not report the confidence level or the exact method used for the primary interval. No detailed statistical analysis plan is reported. Consequently, the interval should be read as the posted uncertainty range, without assuming undocumented modeling choices, covariate adjustments, or corrections for multiple outcomes.

What does an unadjusted p-value say?

A p-value measures how unusual data at least as incompatible with a specified null model would be, if that model and the calculation assumptions were correct. It is not the probability that the null hypothesis is true, the probability that the result occurred by chance, or a measure of clinical importance. The primary unadjusted p-value is 0.242. The registry record does not report a multiplicity adjustment or a prespecified decision threshold, so this value should not be treated as a stand-alone verdict about the intervention.

For secondary binary outcomes, the comparisons are expressed as risk differences: the difference between the observed proportions with an event in the two groups. A negative risk difference in the posted intervention-minus-control direction indicates a smaller observed proportion in the intervention arm; a positive value indicates a larger one. Confidence intervals quantify uncertainty in these contrasts. The risk differences are unadjusted recalculations from the posted event counts and group sizes. The record also displays relative risks and odds ratios, but these are alternative scales for binary comparisons, not independent findings. With sparse event counts, such measures can be uncertain, and their intervals can be wide.

Why can over-dispersion matter?

In general, over-dispersion means that observed variation is greater than a statistical model expects. For count or binary outcomes, a model that understates variation can produce intervals that are too narrow and tests that appear more decisive than warranted. A model that allows extra variation may better represent clustered or heterogeneous observations, when such a structure is present. The registry record does not report that an over-dispersion assessment or a model of this kind was used for these outcomes. The posted binary comparisons are simple unadjusted summaries, so over-dispersion should not be presumed either present or addressed.

What is and is not documented?

The record identifies the randomized parallel design, the masking classification, the outcome definitions, and posted group summaries. It lists no sponsor-reported analyses, and it does not report the original statistical plan, model specifications, handling of missing data, baseline adjustment, or multiplicity strategy. Those omissions limit the extent to which the posted numerical contrasts can be interpreted as the trial’s complete inferential analysis. They do not prevent description of the observed summaries, but they do make it important to distinguish those summaries from a fully documented confirmatory analysis.

11. Confidence Intervals and Precision

Precision concerns how tightly the data locate an estimated effect. The primary mean difference is 2.29 mmHg, with a confidence interval from -1.544 to 6.124 mmHg. Because that interval spans no difference, the data are compatible with a lower average change in the intervention group, little or no group difference, or a higher average change. The interval is not narrow enough to settle the direction of the underlying difference. The estimate alone should not be read as a precise measure of effect.

The group standard deviations, 8.21 mmHg and 8.34 mmHg, indicate substantial variability in individual changes around the group averages. The primary endpoint summaries include 33 intervention participants and 39 control participants, and only participants completing 32-week blood pressure measures were eligible for this endpoint. Both variability and the number of observed endpoint measurements affect precision. The registry record does not report enough about missing measurements or participant characteristics to assess whether the endpoint subset could affect the estimate.

Confidence intervals for the three posted secondary risk differences also span no difference. For preeclampsia, the interval is -0.165 to 0.061; for pregnancy-induced hypertension, it is -0.275 to 0.078; and for gestational diabetes, it is -0.115 to 0.123. Those ranges reflect uncertainty in the respective unadjusted risk differences, not certainty that the true differences are zero. They also do not account for the fact that several outcomes were examined; a multiplicity procedure is not reported in the registry record.

Confidence intervals are more informative than a threshold-based reading of p-values because they show both direction and a range of plausible estimates under the calculation method. They still do not establish clinical importance on their own. The registry record does not state a minimum clinically important difference for systolic blood pressure or for the secondary outcomes. The posted intervals therefore describe statistical precision, while the practical importance of values within them cannot be determined from this record alone.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are illustrations based on observed effects, not a report of the trial’s original design calculations. For these continuous and binary outcomes, the figures are participants per arm, not total event counts. The planning assumptions listed in the registry are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Each scenario targets a stated fraction of the observed effect. For example, planning for 75% of the observed primary effect requires 365 participants per arm for 80% power and 489 participants per arm for 90% power. The figures for the other outcomes use their own observed effects.

The 80% power column describes a design that, under the stated assumptions and if the targeted effect were the true effect, would reject the null hypothesis in 80% of repeated studies. The 90% column describes the corresponding design with a greater chance of detecting that target effect. These are long-run design properties, not guarantees for an individual study. The planning illustrations are not observed power.

Smaller target effects require more participants because they are harder to distinguish from random variation. Thus, planning for 75% or 50% of an observed effect produces larger participant requirements than planning for the full observed effect. This is especially consequential when an observed effect is small: a small estimate can translate into very large planning figures, as in the gestational diabetes illustration. Such figures should be read cautiously because they depend on the observed effect, which is itself uncertain, and on the stated approximation assumptions.

The registry record does not report the original sample-size justification or the assumptions used when the trial was designed. These illustrations should not be used to infer that the completed trial was adequately or inadequately powered under its original plan. They show how planning requirements vary under the listed hypothetical assumptions and target effects.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 2.290; pooled standard deviation σ = 8.281.
2. n = 2 × (1.96 + 0.842)² × 8.281² / 2.290² = 205.3, rounded up to 206 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 2.29                      # observed difference in means
sigma <- 8.28082466562704                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(4291560)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 206 (80% power), 275 (90% power)
 75% of observed effect: n per arm = 365 (80% power), 489 (90% power)
 50% of observed effect: n per arm = 822 (80% power), 1,100 (90% power)
power.t.test: 206.2 
Simulated power at n = 206 per arm: 0.801 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when a study evaluates several outcomes or performs several statistical tests. Even when each test is considered on its own, the chance of at least one apparently unusual result can increase as the number of tests grows. Researchers may address this by prespecifying a primary outcome, using a testing hierarchy, adjusting significance thresholds, or controlling another error rate. Such choices affect how confirmatory claims should be interpreted. The registry identifies a primary outcome and lists multiple secondary outcomes, but a multiplicity strategy is not reported in the registry record.

The primary endpoint is clearly designated as change in systolic blood pressure from baseline to approximately 32 gestational weeks. This makes it possible to distinguish the principal question from the secondary pregnancy outcomes. However, the record lists no sponsor-reported analyses and does not provide the original statistical analysis plan. It is therefore not possible to determine whether the displayed comparisons follow a prespecified hierarchy, whether other analyses were planned, or whether any multiplicity adjustment was performed. The unadjusted p-values should not be interpreted as if those details were known.

Missing data are also important. The primary endpoint population explicitly includes only participants who completed blood pressure measures at the 32-week follow-up visit. The record does not report why other participants lack endpoint data, how missingness was handled in any sponsor analysis, or whether the observed endpoint participants differ from those without measurements. If completion is related to blood pressure, intervention adherence, or other participant characteristics, an analysis limited to completers could differ from an analysis of all randomized participants. The available record does not establish whether that occurred.

For the secondary outcomes, the registry posts group counts and comparisons for three outcomes, but the handling of missing outcome status is not reported. An analysis population based on complete outcome information could also differ from the randomized population. The record does not describe an intention-to-treat analysis, per-protocol analysis, imputation procedure, or sensitivity analysis. These are not details to infer from the posted summaries; they are not reported in the registry record.

The number of outcome measures is listed as 22, and the number of analyses is listed as 0. The latter is consistent with the absence of sponsor-reported analyses in this record, but it does not clarify what analyses may have been conducted outside the registry posting. The most defensible interpretation is limited to the posted group summaries and unadjusted comparisons, with multiplicity and missing-data procedures undocumented.

15. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: preeclampsia (12.7%), hospitalization for urinary tract infection (1.9%), fetal abnormality (abdominal mass) detected via ultrasound (1.8%).

The registry lists serious adverse events for the Prenatal Heart Smart Intervention group among 53 participants at risk: 5 were affected. For Usual Care (Control), 8 of 55 participants at risk were affected. Deaths are listed as 0 in each group. The record also lists other, non-serious adverse events as affecting 35 of 53 participants in the intervention group and 41 of 55 in the control group. These are counts from the registry’s adverse-event summaries; they should be read within their respective groups, not as evidence that an event was caused by the assigned exercise.

The listed serious-event terms include Preeclampsia at 12.7%, Hospitalization for Urinary Tract Infection at 1.9%, and Fetal abnormality (abdominal mass) detected via ultrasound at 1.8%. The registry presentation does not clarify the denominator or group-specific distribution for these term percentages in the information recorded. They should therefore be read as listed terms and percentages, not assigned to a particular arm or interpreted as comparative risks.

Adverse-event counts alone do not establish causation, comparative safety, or the clinical severity of every event. The registry record does not report further event-level timing, attribution, or comparative statistical analyses. These figures describe what was posted and should be interpreted alongside the trial’s population and follow-up context.

16. What the Result Does, and Does Not, Mean

The posted primary result estimates a mean difference of 2.29 mmHg in change in systolic blood pressure, comparing Prenatal Heart Smart Intervention with Usual Care (Control). Its confidence interval, -1.544 to 6.124 mmHg, includes no difference and spans values in both directions. The result therefore does not provide a precise estimate of the direction or size of the underlying group difference. The unadjusted p-value of 0.242 should not be treated as proof that the groups are the same.

Conversely, the estimate and interval do not establish that the intervention produced a meaningful benefit or harm. The interval includes a range of possible differences, and the registry record does not state a threshold for clinical importance. The posted summaries are descriptive, unadjusted comparisons, and the record contains no sponsor-reported analysis for the endpoint. They should not be presented as a definitive causal conclusion about the stretching intervention.

The comparison concerns two activity approaches in late pregnancy: a stretching program added to usual care and facilitator calls, versus usual care with facilitator calls and walking. It does not compare exercise with no exercise, and it does not isolate the contribution of supportive calls. The endpoint also concerns blood pressure change over a limited follow-up interval; it does not by itself answer whether there were differences in pregnancy complications, delivery outcomes, or longer-term cardiovascular health.

Three secondary outcomes have numerical comparisons, with uncertainty in each. Results for other registered outcomes are not reported in the registry record, and a strategy for interpreting multiple outcomes is not reported. The safety summaries list serious and other adverse events, but counts do not establish that the assigned activity caused them or that the groups differ in safety.

Overall, the record supports a cautious description of the observed results and their uncertainty. It does not support a claim that stretching is effective or ineffective, nor does it establish equivalence between the approaches. Conclusions about clinical value would require a more complete account of the planned analysis, missing outcome data, and results for the registered outcomes.

17. Why This Trial Matters Statistically

This trial illustrates why a point estimate should be read together with its uncertainty. The primary mean difference is positive, but its interval crosses no difference and extends in both directions. Looking only at the point estimate would make the result appear more definite than the data support; looking only at whether a p-value crosses a conventional threshold would discard information about the range and direction of estimates compatible with the data.

It also highlights that endpoint populations and enrollment describe different things. Enrollment is listed as 224, whereas the primary endpoint summaries include participants who completed the 32-week blood pressure measures. The registry does not explain the difference or report a missing-data analysis. This distinction matters because precision and generalizability depend on who contributed endpoint measurements, not just on the enrollment figure.

The trial’s comparison is clinically specific: stretching added to usual care and facilitator calls versus walking with usual care and calls. Recognizing that structure prevents an overly broad interpretation as a comparison of activity against inactivity. The continuous primary endpoint and the binary secondary pregnancy outcomes also answer different statistical and clinical questions. Their results cannot be combined into one simple conclusion without a prespecified analysis approach.

Finally, the record demonstrates the limits of registry result summaries. It lists several outcomes and adverse-event counts, but sponsor-reported analyses, multiplicity procedures, the original statistical plan, and details of missing-data handling are not reported. A careful reading separates what can be described directly from what would require those missing analytic details. That separation is central to sound interpretation of clinical trial evidence.

18. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several limitations are specific to the information recorded for this trial. The primary blood pressure endpoint is restricted to participants who completed the 32-week follow-up measures. The posted endpoint summaries include 33 participants in the intervention group and 39 in usual care, but the registry does not explain why other enrolled participants are not represented in these summaries. Without information about missing measurements and participant characteristics, the effect of this restriction cannot be assessed.

The registry does not report the sponsor’s statistical analyses, even though it gives outcome summaries and comparison estimates. It also does not report the original analysis plan, adjustment for baseline blood pressure, or handling of missing data. The displayed comparisons are unadjusted recalculations from the posted summaries. They may not capture any planned or sponsor-conducted analysis that is not included in the record.

The registry lists multiple outcomes, but numerical results are available for only three secondary outcomes in addition to the primary result. Numerical results for the other registered outcomes are not reported in the registry record. This limits assessment of the complete pattern of maternal and delivery outcomes. A multiplicity strategy is also not reported, which makes the unadjusted secondary comparisons less suitable for confirmatory interpretation as a group.

Further design details are limited. The record identifies the trial as single-masked but does not identify who was masked or describe the masking procedures. It does not report the randomization method, allocation concealment, adherence to the activity programs, or the original sample-size justification. The primary interval is wide enough to leave uncertainty about both direction and size, and no threshold for a clinically important blood pressure change is reported. These limitations constrain both statistical and clinical interpretation without establishing that the trial was conducted improperly.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Promoting Stretching Exercise to Reduce Cardiovascular Health Risk in Late Pregnant Women With Obesity — NCT04291560.
• Registry record last updated 2025-11-19; status last verified 2025-01.
• Results first posted 2025-11-17.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

22. Record Summary

NCT04291560 is a completed randomized, single-masked, parallel-group trial sponsored by the University of North Carolina, Chapel Hill. Enrollment is listed as 224. It compares Prenatal Heart Smart Intervention, which includes a home stretching program alongside usual care and facilitator calls, with Usual Care (Control), which includes walking alongside usual care and facilitator calls.

The primary outcome is change in systolic blood pressure from approximately 27 to approximately 32 gestational weeks among participants completing the follow-up blood pressure measures. The posted mean difference is 2.29 mmHg, with a confidence interval from -1.544 to 6.124 mmHg and an unadjusted p-value of 0.242. The interval includes no difference and indicates uncertainty about the estimate.

Numerical results are posted for three secondary pregnancy outcomes. Sponsor-reported analyses, the original statistical plan, multiplicity procedures, and details of missing-data handling are not reported in the registry record. Results for the other registered outcomes are also not reported in the registry record.